LU-14074 scripts: automatic LNet unconfigure

LU-14074 scripts: automatic LNet unconfigure

After using the lnetctl utility a reference count is taken on the LNet
modules. lnetctl lnet unconfigure is called in order for
lustre_rmmod to remove the LNet module.

Signed-off-by: Cyril Bordage <cbordage@whamcloud.com>
Change-Id: I7251a0c62c45da7b3cb0fddea97394b32cb6902a
Reviewed-on: https://review.whamcloud.com/41698
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>